Traveling image direct viewing tube with rotatable storage cylinder



Mw 9? w67 N. .sA KoDA ETAL Slgfl@ TRAVELING IMAGE DIRECT VIEWING TUBE WITH ROTATABLE STORAGE CYLINDER Filed April l0. 1964 3 Sheets-Sheet l MW 9 i967 N. J. KODA ETAL. Zwl

TRAVELING IMAGE DIRECT VIEWING TUBE WITH ROTATABLE STORAGE CYLINDER Filed April lO, 1964 3 Sheets-S1166?. L

l" W Q W57 N. J. KODA ETAL TRAVELING IMAGE DIRECT VIEWING TUBE WITH ROTATABLE STORAGE CYLINDER 3 Sheets-Sheet 5 Filed April l0, 1964 3,319,l TRAVELIING lill/HAGE DERECT VEEWENG TUBE 'vVlTl'rl RUE/ir'llsiilbl STGRAGE CYLNDER Nobuo Jl. Koala, Vista, and Leon S. Yaggy, North Carlshad, Calif., assignots to Hughes Aircraft Company,

Culver City, Calif., a corporation of Delaware Filed Apr. it), 1964, Ser. No. 353,913 lil Claims. (Cl. 313-449) This invention relates to a traveling image storage tube capable of providing a visual display which permits direct, continuous, and real time observations of data acquired, for example, from line scan radar systems. More particularly, the invention relates to a visual display device which presents stored images capable of moving with respect to the observer at a rate and direction corresponding to or simulating the velocity and direction of a moving vehicle.

It is desirable in many fire or bombing control systems to provide a picture or map-like image of the navigational problem involved. Thus, if the observer is moving with respect to a target and the terrain, it is desirable to continuously display the target and terrain as it moves. When such a display is attempted with conventional cathode ray tubes it is necessary, even with tubes capable of presenting stored displays, to constantly and repetitively erase and reform the entire display. This constant and repetitive erase and rescan procedure involves a considerable amount of associated circuitry which may lbe bulky and of vconsiderable weight and complexity.

lt is therefore an object of the present invention to provide an improved storage display device.

Another object of the invention is to provide an improved traveling image storage tube.

Another object of the invention is to provide an improved storage display device capable of presenting an image which moves with respect to an observer.

These and other objects and advantages of the invention are realized by providing a direct-viewing visual display storage tube having at least a moving storage target which controls the passage of viewing electrons to a viewing target which may be viewed through or at one portion of the tube envelope by an observer. The storage target is caused to move past such point of observation at a rate corresponding to the actual rate of change of the information lbeing displayed. Since the storage target establishes and controls the visual display, scanning and moving the storage target results in a moving display of information.

The invention will be described in greater detail by reference to the drawings in which:

FIGURE l is a side elevational view in section of a traveling image storage tube according to the invention;

FIGURE 2 is a front elevational View in section of the traveling image storage tube shown in FEGURE l;

FIGURE 3 is a side elevational view in section of another embodiment of a traveling image tube according to the invention; and

FIGURE 4 is an elevational view in section of a detail of the traveling image storage tube shown in FIG- URE 2.

Before proceeding to a detailed description of the present invention it may be helpful to briefly describe the operation of a direct-viewing electronic storage tube of the type to which the present invention appertains. A complete description of such a storage tube is found in US. Patent 2,790,929 to E. E. Herman and G. F. Smith, assigned to the instant assignee. Such a storage tube comprises a target assembly which includes a storage target and a viewing screen. Two electron guns are provided: one gun (hereinafter called the Lwriting gun) causes the formation of a charge pattern on the storage `nited States Patent Office dlldS Patented May 9, i967 target corresponding to the information to be presented; and the other gun (hereinafter called the dood Ior viewing gun) renders this charge pattern visible on the viewing screen by producing a flood of electrons which peneates the storage target in accordance with the charge pattern thereon. As contemplated by the aforementioned patent to E. E. Herman and G. F. Smith, the formation of the storage pattern on the storage target is usually achieved by the phenomenon of secondary electron emission although the phenomenon of bombardment induced conductivity may also be used in accordance with the teachings of N. H. Lehrer in U.S. Patent No. 3,086,139. At any rate a pattern of charges, formed on the storage target by either phenomena, comprises potentials which are more or less negative with respect to the tlood or viewing gun cathode so that this charge pattern controls the passage of the flood electrons from the viewing gun to the viewing screen. The flood electrons are collimated over the entire area of the storage target but only pass through areas of the storage target which are charged less negatively with reference to the viewing gun cathode.

Referring now to FGURES l and 2 an evacuated container 4 is shown comprising a cylindrical Section 5 whose end portions are closed by convex shaped sections 6 and 7. The -cylindrical section 5 and the end sections 6 and 7 may be made of glass, for example, and are hermetically sealed to each other to provide the container d which may be evacuated and maintained hermetic during operation. ln the end section 6 are mounted a pair of pin sockets 8 and 9 such as are found in more conventional cathode ray tubes for making the necessary electrical connections to the electrodes and other components Within the envelope 4i. Thus, for example, the pin socket member 8 is utilized for providing the necessary electrical connections to the ood gun itl While the pin socket member 9 is utilized for making electrical connections to the writing gun 3i). In the opposite end section 7 an hermetically sealed bearing member 5t) is disposed in which is mounted a shaft Sti which is disposed along the axis of the cylindrical section S so as to permit the shaft 58 to be rotated lby driving means located externally of the envelope 4 Without irnpairing the hermeticity thereof. This bearing member Sti and its structure which permit the shaft 58 to be rotated by an external driving -force vwill be de scribed in greater detail hereinafter.

Within the container d is a cylindrical member 22 of electrically non-conducting material such as glass, for example. rThe glass cylinder 22 is disposed coaxially within the cylindrical section 5 of the envelope 4 and has an open end facing the end section 6 thereof. The end of the glass cylinder 22 which faces the end section 7 of the envelope 4 is mounted on a circular plate member 20 which has a centrally disposed bore therein and to which the end of the driving shaft S8 is aixed by means of a bushing member 2l. Further rigidity and strength to the mounting of the glass cylinder 22 to the driving shaft S8 may be attained by means of a conically shaped bracket or supp-ort member 23 which is secured to the circular plate 20' and to another portion of the driving shaft 58 by means of a second bushing member Z5. Preferably, the circular plate member Ztl may also be of an electrically non-conductive material such as glass, for example.

In addition to serving as a target and/ or electrode supporting member, which will be described in greater detail hereinafter, the glass cylinder 22 constitutes the viewing target 2li of the tube of the present invention. Thus, on the inner surface of the glass cylinder 22 is provided a phosphor layer 24 which is adapted to emit light in response to the impingement thereon of electrons. Also,

as is a well-known practice in the cathode ray tube art, an electron transparent conductive coating or layer 26 of aluminum, for example, may be disposed over the phosphor layer 24 for the purpose of reflecting light produced by the phosphor layer 24 toward the observer and for aiding in maintaining a high volta-ge accelerating potential on the viewing target 20.

Disposed within the glass cylinder 22 is a storage target assembly 14 in the form of an electroformed metal mesh cylinder 16 which is coaxial with the axis of the cylindrical section of the envelope 4. The mesh cylinder 16 may be formed from a nickel screen, for example, having about 250 meshes per inch and a thickness of about 0.001 inch. The surface of the mesh cylinder 16 facing away from the viewing target cylinder 22 is provided with a thin coating 18 of secondary emissive dielectric material to constitute a storage surface capable of acquiring an electric charge in response to impingement thereon of electrons. The dielectric material may be capable of acquiring such a charge by the phenomena of secondary electron emission and/or electron bombardment induced conductivity. In the case of a secondary electron emissive material a layer of about 20,000 angstroms may be utilized. Such a layer may be provided by evaporating magnesium fluoride, for example, onto the mesh 16. The storage mesh cylinder 16 is mounted to and within the glass cylinder 22 and is adapted to rotate therewith about their common axis by means of a glass ring 27 which is fused to peripheral portions of both the glass cylinder 22 and the mesh cylinder 16.

Likewise disposed within the storage target cylinder 14 is a collector electrode 12 comprising an electroformed rnetal mesh cylinder. The collector mesh cylinder 12 which may be of nickel, for example, is mounted to the storage mesh 16 an-d hence to the glass cylinder 22 by means of a glass ring 29 which is fused to peripheral portions of both the storage mesh cylinder 16 and the collector mesh cylinder 12 so as to electrically isolate the two metallic cylinders from each other.

It will thus be understood that by the arrangement shown and described the various cylindrical members mounted within the envelope 4 may be rotated together about a common axis and are all provided with an open end which permits the necessary electrical connections to be made to the various cylindrical electrode structures. Such electrical connections may be provided by flexible lead wires or commutator brush arrangements and the like from the pin socket member 9, for example.

Mounted Within the envelope 4 is an electron gun 30 for forming an electron beam of elemental cross sectional area by which the storage target 14 may be scanned as will be described in greater detail hereinafter. The axis of the gun is disposed in a direction normal to the surface of the storage target 14. The electron ygun 30 includes a source of electrons or cathode beam forming members as well as beam deection members according to conventional electron gun techniques. It is not deemed necessary to describe such a scanning electron gun in further detail. The gun 30 may be mounted by means of a strap or bracket member 31 which is secured to the end section 6.

Disposed within the envelope 4 and particularly coaxially within the cylindrical section 5 is a ood gun 40 comprising a line cathode 42 and line aperture forming or defining members 43. The line cathode 42 and the aperture defining members 43 may be mounted by means of a glass support rod 45 which is affixed to the end section 6 of the envelope 4. The line cathode 42 is arranged with respect to the aperture defining members 43 so that a ood beam of electrons may be formed and caused to impinge over the storage target 14.

The storage and display operation will be described before proceeding with a further description of the traveling image storage tube of the invention. It will be understood that the storage and display functions described 4 herein are conventional and a full description thereof may be found in U.S. Patent 2,790,929 issued to E. E. Herman and G. F. Smith entitled Direct-Viewing Half-Tone Storage Device. In operation the dielectric storage surface 18 is charged negatively with respect to the line cathode 42 of the flood gun 40 by applying negative pulses thereto. This is done in order to ensure the erasure of any previous stored charges on the storage surface. This pulsing establishes a quiescent potential on the storage surface of about 5 volts negative with respect to ground. In this condition flood electrons cannot penetrate the storage screen and will be returned to the collector mesh 12 which is maintained at a potential of about 150 volts.

Upon the application of intelligence signals to the writing electron gun 30 and its associated defiection system, the writing electron beam is intensity modulated and strikes the storage surface with such energy that secondary emission therefrom is very high', i.e., many secondary electrons are emitted Vfor each incident primary electron. These secondary electrons are attracted away from the storage surface to the collector grid 12, thus causing the formation of a charge pattern on the storage surface in accordance with the applied intelligence signals. Potentials ranging from a uniformly positive white value to a uniformly negative black value are capable of being stored. The brightness of the viewing screen ranges from 0-l00% brightness of a combination of storage surface potentials ranging from about -8 volts down to about 0 volts. The whole range from black through grey to white is thus achieved in an increment of about 7 volts on the storage surface. Potentials in this range are established according to the current of the Writing electron beam, which in turn, as noted previously, is intensity modulated according to the applied intelligence signals.

Thus, those areas of the storage surface which are charged positively in this manner permit flood electrons to pass through the storage target assembly 14 to strike the viewing target 20 producing a visual presentation in accordance with the number of impinging flood electrons which in turn depends upon the storage surface potentials. In order to erase stored charges from the storage surface, the storage screen 16 may be periodically pulsed positively by pulses whose magnitude is approximately equal to the range of potentials over which half-tone operation takes place, for example, 9 volts. Erasure of displays in the tube of the present invention will be described in greater detail hereinafter in connection with the description of the traveling image function of the invention.

While the invention has been described in connection with a secondary emission type storage target it will be understood that the practice thereof is by no means limited to this type of target. Alternatively, a storage target utilizing the phenomenon of bombardment induced conductivity may be used to equal advantage in the traveling image storage tube of the invention. A suitable bombardment induced conductivity storage target and the operation thereof are fully described by N. H. Lehrer in his U.S. Patent No. 3,086,139 assigned to the instant assignee.

The flood electron beam emitted by the line flood gun 40 covers approximately 160 of arc as indicated by the dotted lines in the drawings. Since the line Hood gun is located on the axis of the cylindrical target elements as described previously, all ood electron trajectories are radial which precludes the necessity of providing any collimating electrodes as is required in conventional cathode ray storage tubes of this type.

Target information is written on the storage target 14 by the single writing gun 30 having just one coordinate of deflection (i.e., horizontally) since the other coordinate (i.e., vertical) is provided by rotation of the storage target 14 as will be more fully described hereinafter. The line scan writing on the storage target 14 by the writing gun 30 is accomplished just prior to the point at which the flood beam-illuminated viewing region occurs.

The container cylinder is provided with a viewing window section 5 through which the display on the viewing target may be observed. This window section S may cover about 100 of arc, for example, and the remainder of the container cylinder 5 may be opaque to reduce dilution of the light produced in the tube by the viewingg target with ambient light.

In operation, the viewing target Ztl, the storage target 14, and the collector target mesh l2 are all caused to rotate together past the observation window section 5 rotating the shaft 53 on the axis at a rate corresponding to the apparent rate of change of the image. The target information or video signals are applied in conventional manner to the writing electron gun Si? so as to modulate the electron beam formed thereby in intensity. The electron beam produced by the writing gun is caused to scan this storage target ld in line fashion just prior to the point at which the viewing target moves into observable position with respect to the window section 5'. The electrostatic storage pattern developed by the writing beam on the storage target liriis rendered visible on the viewing target 20 by means of the llood electrons from the flood gun 49. Information stored on the storage target 14 may be removed by electronically pulsing the storage target mesh 16 with a series of pulses of about 9 volts amplitude at low duty cycles so that fading of the stored information can occur partially over the viewed region of the viewing target with complete erasure occurring after passing the point of observation. Thus, partial erasure will occur during viewing and complete erasure will be accomplished by the time the full semi-circle of flood gun illumination is traversed by the information stored on the storage target. If such partial erasure during viewing is undesirable, an additional electron gun may be incorporated within the tube for erasure of stored information after viewing thereof so as to scan the storage target with an electron beam of energy level lower than that required for secondary emission greater than unity. In the case of a bombardment induced conductivity target this additional erase gun would be operated at an energy level likewise capable of charging the storage target in a direction opposite to that of the writing gun 30. Such selective erasure is fully described in the aforementioned patent to N. H. Lehrer and it is not believed that further detailed description thereof is necessary herein.

Another embodiment of the present invention is shown in FIGURE 3. Here the viewing target cylinder is eliminated so that only two rotating electrode members are required. In this embodiment the phosphor layer 24 is applied directly on the inside surface of the window section 5 of the outer container envelope 5 and the metal layer 26 is applied on the back of the phosphor layer 2d. While it is not necessary that the collector target rotate with the storage target it may be more convenient to mount the collector mesh l2 as described beforehand on the rotating storage target lll. It will be appreciated that operation of this tube is identical with that shown and described in connection with FIGURES l and 2.

In FIGURE 4 apparatus is shown for permitting the internal shaft S8 to be rotated by means of an externally disposed driving member (not shown). The sealed bearing member 50 is shown as delining an enclosure having a driving shaft 52 extending through one wall thereof and terminating therewithin with a second shaft 58 extending through the opposite wall and into the tube envelope as described previously. The ends of the shafts 52 and 5S are provided with angularly disposed portions 52 and 58 respectively which are parallel to each other and connected by means of a pin 56. The portion of the shaft 52 which is disposed within the chamber formed by the bearing member 50 is contained within a bellows member 5d which is hermetically sealed to the inside wall portion of the enclosure Stl and to the pin Se where this pin extends through the end of the bellows for connection with the angular portion 58 of the shaft 5S. Thus, the shaft 52 can rotate and have its rotational motion paired to the shaft 58 without impairing the hermeticity of the sealing enclosure member 5d. Other means are readily available for driving the shaft S8 by an external drive and the prac tice of the invention is by no means limited to the bellows arrangement shown which is only typical. Thus the target cylinders could be driven magnetically, for example, if desired.

There thus has been described a novel traveling image storage tube device.

What is claimed is:

l. A direct-viewing cathode ray storage tube device comprising:

(l) an evacuated container having therein:

(A) a movable storage target member;

(B) a viewing target member adjacent said storage target member and adapted to be viewed through said evacuated container at a predetermined portion thereof;

(C) a lirst electron gun means for scanning said storage target member with an electron beam so as to establish thereon an electrostatic charge pattern corresponding to information to be displayed;

(D) -a second electron gun means for flooding and penetrating said storage target member with viewing electrons in accordance with said charge pattern thereon whereby a visual display corresponding to said charge pattern is established on said viewing target member by said viewing electrons;

(E) a collector target member for receiving secondary electrons produced by said storage target member;

(2) and means for moving said storage target member in a predetermined direction past said predetermined portion of said container.

2. A direct-viewing cathode ray storage tube device comprising:

(l) an evacuated container having therein:

(A) a movable target assembly comprising:

(a) a viewing target member; (b) a storage target member; (c) and a collector target member;

(B) a first electron gun means for scanning said storage target member with an electron beam so as to establish thereon an electrostatic charge pattern corresponding to information to be displayed;

(C) a second electron gun means for flooding and penetrating said storage target member with viewing electrons in accordance with said charge pattern thereon whereby a visual display correspending to said charge pattern is established on said viewing target member by said viewing electrons;

(D) means to permit observation through said container of at least a portion of said viewing target member;

(2) and means for moving said target assembly in a predetermined direction past said observation means of said container.

3. A direct-viewing cathode ray tube device comprising:

(l) an evacuated cylindrical container having therein:

(A) a viewing target member disposed on an inner surface of said cylindrical container and adapted to be viewed therethrough;

(B) a cylindrical storage target member adapted to be rotated within said cylindrical container about a common axis therein;

(C) a cylindrical collector target member disposed within said cylindrical storage target member and adapted to be rotated about said common axis;

(D) a first electron gun means for scanning said storage target member with an electron beam so as to establish thereon an electrostatic charge pattern corresponding to information to be displayed;

(E) a second electron gun means for flooding and penetrating said storage target member with viewing electrons in accordance with said charge pattern thereon whereby a visual display corresponding to said charge pattern is established on said viewing target member by said viewing electrons;

(2) and means disposed outside said cylindrical container for rotating said storage target member and said collector target member about said common axis.

4. A direct-viewing cathode ray storage tube device comprising:

(1) an evacuated cylindrical container having therein:

(A) a cylindrical viewing target member adapted to be rotated about a common axis in said cylindrical container and viewed through a predetermined portion thereof;

(B) a cylindrical storage target member disposed within said cylindrical viewing target member and adapted to be rotated about said common axis;

(C) a cylindrical collector target member disposed within said cylindrical storage target member and adapted to be rotated about said common axis;

(D) a rst electron gun `means for scanning said storage target member with an electron beam so as to establish thereon an electrostatic charge pattern corresponding to information to be displayed;

(E) a second electron gun means for flooding and penetrating said storage target member with viewing electrons in accordance with said charge pattern thereon whereby a visual display corresponding to said charge pattern is established on said viewing target member by said viewing electrons;

(2) and means disposed outside said cylindrical container for Arotating said target members.

5. A directviewing cathode ray storage tube device comprising:

(1) an evacuated container having therein;

(A) a viewing target member disposed adjacent an inner surface of said evacuated container and adapted to be viewed therethrough;

(B) a storage target member adjacent said viewing target member adapted to be rotated within said evacuated container about a predetermined axis and comprising:

(a) a mesh storage member; and

(b) a dielectric material disposed on the surface of said mesh member on the side thereof away from the direction of said viewing target member and being capable of having an electrostatic charge pattern formed thereon in response to electron bombardment;

(C) a `collector target member disposed adjacent said storage target member and adapted to be rotated about said predetermined axis;

(D) a rst electron gun means for scanning said dielectric material of said storage target member with an electron beam so as to establish thereon an electrostatic charge pattern corresponding to the information t-o be displayed;

(E) a second electron gun means for ooding and penetrating said storage target member with viewing electrons in accordance with said charge pattern thereon whereby a visual display corresponding to said charge pattern is established on said viewing target member by said viewing electrons;

(2) and means disposed outside said cylindrical container for rotating said storage target member and said collector target member' about said predetermined axis.

6. A direct-viewing cathode ray storage tube device comprising:

(l) an evacuated cylindrical container having therein:

(A) a cylindrical viewing target member adapted to be rotated about a common axis in said cylindrical container and viewed through a predetermined portion thereof;

(B) a cylindrical storage target member disposed within said cylindrical viewing target member and insulatingly affixed to peripheral portions thereof lso as to be rotatable therewith about said common axis;

(C) a cylindrical collector target member disposed within said cylindrical storage target member and insulatingly afxed to peripheral portions thereof so as to be rotatable therewith about said common axis;

(D) a rst electron gun means for scanning said storage target member with an electron beam so as to establish thereon an electrostatic charge pattern corresponding to information to be displayed;

(E) a second electron gun means for flooding and penetrating said storage target member with viewing electrons in accordance with said charge pattern thereon whereby a visual display corresponding to said charge pattern is established on said viewing target member by said Viewing electrons;

(2) and means disposedoutside said cylindrical container for rotating said target members.

7. The invention according to claim 6 wherein said storage and collector targets comprise electrically conductive mesh cylinders and said storage target member has a layer 4of dielectric material capable of having an electrostatic charge pattern established thereon in response to electron bombardment thereof disposed on the surface thereof facing said collector target member.

S. A direct-viewing cathode ray tube device comprising:

(l) an evacuated cylindrical container having therein:

(A) a viewing target member disposed on an inner surface of said cylindrical container and adapted to be viewed therethrough;

(B) a cylindrical storage target member to be rotated within said cylindrical container about a common axis therewith;

(C) a cylindrical collector target member disposed within said cylindrical storage target member and adapted to be rotated about said common axis;

(D) a first electron gun means disposed Within said cylindrical collector target member for scanning said storage target member with an electron beam;

(E) a second electron gun means disposed within said cylindrical collector target member for flooding and penetrating said storage target member with viewing electrons in accordance with said charge pattern thereon whereby a visual display corresponding to said charge pattern is established on said viewing target member by said viewing electrons;

(2) and means disposed outside said cylindrical container for rotating said storage target member and said collector target member about said common axis.

9. A direct-viewing cathode ray tube device comprising:

(1) an evacuated cylindrical container having therein:

(A) a cylindrical viewing target member adapted to be rotated about a common axis in said cylindrical container and viewed through a predetermined portion thereof;

(B) a cylindrical storage target member disposed within said cylindrical viewing target member and adapted to be rotated about said common axis;

(C) a cylindrical collector target member disposed within said cylindrical storage target member and adapted to be rotated about said common axis;

(D) a irst electron gun means disposed adjacent said common axis for scanning said storage target member with an electron beam so as to establish thereon an electrostatic charge pattern corresponding to information to be displayed;

(E) a second electron gun means disposed adjacent said common axis for ooding and penetrating said storage target member with viewing electrons in accordance with said charge pattern thereon whereby a visual display corresponding to said charge pattern is established on said viewing target member by said viewing 5 electrons;

(2) and means disposed outside said cylindrical container for rotating said target members. 10. The invention according to claim 7 wherein said rst and second electron gun means are disposed adjacent 10 said common axis.

References Cited by the Examiner UNITED STATES PATENTS 2,330,682 9/1943 Clothier et al 313-68 15 3,042,825 7/1962 Bambara et al. 313-89 3,123,733 3/1964 Freeman 313-146 3,129,284 4/1964 Bock 313-89 3,204,238 S/1965 Skellett 313-149 20 JAMES W. LAWRENCE, Primary Examiner.

V. LAFRANCHI, Assistant Examiner. 

1. A DIRECT-VIEWING CATHODE RAY STORAGE TUBE DEVICE COMPRISING: (1) AN EVACUATED CONTAINER HAVING THEREIN: (A) A MOVABLE STORAGE TARGET MEMBER; (B) A VIEWING TARGET MEMBER ADJACENT SAID SOTRAGE TARGET MEMBER AND ADAPTED TO BE VIEWED THROUGH SAID EVACUATED CONTAINER AT A PREDETERMINED PORTION THEREOF; (C) A FIRST ELECTRON GUN MEANS FOR SCANNING SAID STORAGE TARGET MEMBER WITH AN ELECTRON BEAM SO AS TO ESTABLISH THEREON AN ELECTROSTATIC CHARGE PATTERN CORRESPONDING TO INFORMATION TO BE DISPLAYED; (D) A SECOND ELECTRON GUN MEANS FOR FLOODING AND PENETRATING SAID STORAGE TARGET MEMBER WITH VIEWING ELECTRONS IN ACCORDANCE WITH SAID CHARGE PATTERN THEREON WHEREBY A VISUAL DISPLAY CORRESPONDING TO SAID CHARGE PATTERN IS ESTABLISHED ON SAID VIEWING TARGET MEMBER BY SAID VIEWING ELECTRONS; (E) A COLLECTOR TARGET MEMBER FOR RECEIVING SECONDARY ELECTRONS PRODUCED BY SAID STORAGE TARGET MEMBER; (2) AND MEANS FOR MOVING SAID STORAGE TARGET MEMBER IN A PREDETERMINED DIRECTION PAST SAID PREDETERMINED PORTION OF SAID CONTAINER. 